A lithium mixed metal oxide is used as a positive electrode active material in a nonaqueous electrolyte secondary battery, such as a lithium secondary battery. The lithium secondary battery has already been put into practical use as a power source for portable telephones, notebook-sized personal computers, and the like, and also attempted to be used in medium and large size applications, such as applications of use for automobiles or electric power storages.
JP-A-2000-195516 specifically discloses Li (Mn0.1Ni0.45Fe0.45) O2 as the conventional lithium mixed metal oxide.